What’s the difference between an air source and ground source heat pump?

what are the pros and cons of air source heat pumps
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    Air source heat pumps are most commonly found in 2 forms: air source and ground source.

    Both operate on the same basis, but as the name suggests, gather their energy from a different source. Other types such as water source are also available but are far less common.

    Air source heat pump

    Pros

    • Cheaper to install
    • Far less disruption (no need for groundworks generally)
    • More efficient in warmer weathers (spring and autumn months where the ambient air temperature is warmer)
    • Qualify for £5,000 government funding via the Boiler Upgrade Scheme (subject to eligibility)

    Cons

    • Maximum output of around 16.5kW, which is roughly enough for your typical 5 bed detached bungalow, or 5 bed Victorian townhouse (based on a standard 100amp single phase electricity supply. Lager units/multiple units can be installed if 3 phase is available).
    • Necessity for external units which some deem unsightly
    • Less efficient than ground source heat pumps when ambient external temperature is very low

    Ground Source Heat Pump

    Pros

    • Maximum output of around 24kW on a standard 100amp single phases electricity supply (larger units/multiple units can be installed if 3 phase is available)
    • Same efficiency all year round (due to the depth of the external heat exchanger pipework being buried at a depth which is consistent all year), meaning on average a ground source heat pump will be slightly more efficient than an air source (when taking an average over 12 months)
    • No external air condenser visible (all pipework outside is buried beneath the ground
    • Qualify for £6,000 government funding via the Boiler Upgrade Scheme (subject to eligibility)

    Cons

    • Expensive to install (generally large amounts of groundworks needed to for the external collector loops). These can be installed in horizontal runs (trenches), or boreholes (if space is limited)
    • Larger space required internally for all the plant and equipment

    Our general guidelines when it comes to air source heat pumps vs ground source heat pumps is the capacity requirement of the property. For example, if your property requires less than 16.5kW to heat then an air source heat pump is generally the most suitable and cost-effective option.

    If your property requires more than 16.5kW to heat, then it is worth investigating ground source heat pumps. Of course, there are exceptions to this rule, and all properties are assessed individually to come up with the best suited technology.

    Dan Loveridge
    Dan Loveridge

    Dan is the managing director at Cinergi, a renewable energy company based in southern England specialising in air source heat pumps and EV charging solutions.

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